Followings are regulations regarding retention of oil on board –
- Adequate means shall be provided for cleaning the cargo tanks and transferring the dirty ballast residue and tank washings from the cargo tanks to a slop tank approved by the Administration.
- The capacity of the slop tanks shall not be less than 3% of the oil carrying capacity of the ship.
- Combination carriers who carry oil tanks in smooth walls are allowed to reduce their slop tank capacity to 1%.
- New oil tankers classed Aframax, VLCC and above must be provided with at least 2 slop tanks.
Slop tanks shall be designed particularly to avoid excessive turbulence.